Filter elements and additive therefor



United States Patent FILTER ELEMENTS AND ADDITIVE THEREFOR Bobby J.Sublett and Cephas H. Sloan, Kingsport, Tenn,

assignors to Eastman Kodak Company, Rochester,

N.Y., a corporation of New Jersey N0 Drawing. Filed Apr. 9, 1965, Ser.No. 447,093

US. Cl. 131266 2 Claims Int. Cl. A24d 1/04; A24f 13/06 ABSTRACT OF THEDISCLOSURE A selective tobacco smoke filter element containing aparticulate additive coated with a water-soluble, weakbasic inorganicsalt which is capable of chemically reacting with and rendering harmlesssubstantially all'hydrogen cyanide vapors contained in the tobacco smokepassing through the filter elements. The organic salt is selected fromthe group consisting of phosphates, phosphites, and carbonates of sodiumand potassium.

This invention relates to tobacco smoke filter elements. Moreparticularly it concerns specially coated powdered additives for tobaccosmoke filter elements and filter elements containing same.

In our US. patent application Ser. No. 425,920, filed J an. 15, 1965,now US. Patent No. 3,297,705 issued Aug. 20, 1968, we disclose use ofcertain water-soluble inorganic salts for removal of substantial amountsof hydrogen cyanide from tobacco smoke by addition to filter elements.While such salts have proved highly successful in cyanide removal wehave noticed in some instances a tendency of these additives to dust offand to 'be not distributed over the filter filaments in as uniform amanner as might be desired. Also, such salts in powder form tend to haveparticles which are sometimes too large to be completely dissolved bythe moisture from the smoke passing through the filter element. Thus, insuch instances optimum filtration efiiciency is not attained. Thereforedevelopment of a filter element with improved hydrogen cyanidefiltration efficiency and an improved water-soluble inorganic saltadditive therefor represent a highly desirable result. After extendedinvestigation we have developed an additive which removes an increasedamount of hydrogen cyanide from tobacco smoke when contained incontinuous filament cellulose acetate filament filter elements. We havealso found that this additive may be used in a highly efficient mannerin conjunction with known tobacco smoke filter element additives.

One object of this invention is to provide a new and improved type oftobacco smoke filter element. Another object is to provide 21 treatedpowder which may be applied to cellulose acetate tow to improveparticulate matter removal and to selectively remove hydrogen cyanide(HCN) from the vapor of tobacco smoke. A further object is to provide amethod for constructing an improved tobacco smoke filter. Still anotherobject is to provide an improved additive for cellulose acetate filtertow.

In its broader aspects our invention involves adding to celluloseacetate tow powders which have water-soluble inorganic salts coated onthe surface thereof, especially the salts of Group Ia elements. Thecoated powders may be applied by vibrating onto the tow.

Inorganic salts which we have found particularly useful according to ourinvention include the sodium and potassium carbonates and phosphites ormixtures of these. Powders (or powders in flake form) which may becoated with these water-soluble inorganic salts to dampen their staticproperties and enhance their application by a vibration techniqueinclude cellulose acetate, cellulose, methyl cellulose, starch, and thelike. The amount of inorganic salt that may be added according to ourinvention is from 1 to 50%, the preferred amount being between 2 and 10%based on the weight of the final filter. The amount of additive coatedwith salt that may be added to the tow according to our invention isbetween 1 and the preferred amount being between 5 and 50%, based on theweight of the final filter.

According to one embodiment of the instant invention a crimped tow maybe spread out to a width of approximately 15 inches as it moves througha cigarette plugmaking machine. A vibrating pan 15 inches in width isplaced directly above and parallel to the tow. In the pan is placed aflake or powder which has been ground to pass through a 50-mesh screenand coated on its surface from a water solution with sodium carbonate orthe like inorganic water-soluble salt amounting to 25% by weight of theflake or powder. The vibrator pan is adjusted to apply the desiredamount of additive, and the additive is vibrated onto the filter tow asit moves through the filter plug-making equipment. As the tow containingthe additive moves through the equipment, the tow is recompacted andwrapped with a paper tape to form a cylindrical-shaped section. Thissection may be cut into any desired length and used either alone as afilter or in combination with other filters to make a dual or multiplefilter.

For a further understanding of our invention, following are severalillustrative examples.

Example I A l0-ft. length of 8 denier/filament (d./f.) crimped celluloseacetate filter tow having 8,000 filaments and weighing approximately 20grams is spread out to a width of 15 inches. Glyceryl triacetate(triglycerin) in the amount of 8% by weight of the tow is applied to thetow by rollers. A dry cellulose acetate powder containing 0.5 g., 50% byweight, sodium carbonate coated on its surface is applied to the towfrom a vibrating pan until 1 g., 5% total additive, based on the weightof the tow, is added. The tow is then recompacted and wrapped with apaper tape. The cylindrical section thus formed is then cut into 20 mm.segments. The 20 mm. segments are attached to king-size cigarettes bymeans of a cellophane tape. The cigarettes are smoked with an automaticsmoking device, and the amounts of total particulate matter (tar) andhydrogen cyanide are determined respectively 'by the method ofMcConnell, et al., in Tobacco Science 4, 55-61 (1960), and substantiallythe method described by Aldridge et -al.. in the Analyst 69, 262 (1944).The amounts of total particulate matter and hydrogen cyanide obtainedfrom the same type filter element containing no additive, and a filterelement containing only powdered sodium carbonate as an additive aresubstantially higher than those obtained with the filters containingcellulose acetate powder coated with sodium carbonate.

Example II A lO-ft. length of 8 d./'f. crimped cellulose acetate filtertow having 8,000 filaments and weighing approximately 20 grams is spreadout to a width of 15 inches. Glyceryl triacetate in the amount of 8%(1.6 g.) by weight of the tow is rolled onto the tow. A dry methylcellulose powder containing 0.8 g., 50% by weight, sodium carbonatecoated on its surface is applied to the tow from a vibrating pan until8% total additive (1.6 g.), based on the weight of the tow, is added.The tow is then recompacted and wrapped with a paper tape to form a rod.The rod is then cut into 20 mm. segments. The 20 mm. segments areattached to king-size cigarettes by means of a cellophane tape, and thecigarettes smoked with an automatic smoking device. The amount of totalparticulate matter (tar) delivered by the cigarette is determined by themethod of McConnell et al., in Tobacco Science 4, 55-61 and the amountof hydrogen cyanide is determined as substantially described by Aldridgeet al., in Analyst 69, 262 (1944).The amounts of total particulatematter and hydrogen cyanide which are obtained from the same type filterelements containing no additive and a filter element containing onlypowdered sodium carbonate as an additive are substantially higher thanthose obtained with the filters containing cellulose acetate powdercoated with sodium carbonate.

Example HI A 10-ft. length of 8 d./f. crimped cellulose acetate filtertow having 8,000 filaments and weighing approximately 20 grams is spreadout to a width of 15 inches. Glyceryl triacetate in the amount of 1.6g., 8% by weight of the tow, is rolled onto the tow. A dry cellulosepowder containing 50% by weight (0.45 g.) potassium carbonate coated onits surface is applied to the tow from a vibrating pan until 45% (9.g.)f the additive, based on the weight of the tow, is added. The tow isthen recompacted and wrapped with a paper tape to form a rod. The rodsare then cut into 20 mm. segments. The 20 mm. segments (filter elements)are attached to king-size cigarettes by means of a cellophane tape, andthe cigarettes smoked with an automatic smoking device. The amounts oftar and hydrogen cyanide delivered by the filter cigarettes aredetermined by the methods described in Examples I and II. The amounts oftotal particulate matter and hydrogen cyanide obtained from the sametype filter element containing no additive and a filter elementcontaining only powdered potassium carbonate as an additive aresubstantially higher than those obtained with the filters containingcellulose acetate powder coated with potassium carbonate.

From the foregoing description and examples it may be seen that we haveprovided a cellulose acetate filter element of increased selectivity forremoval of hydrogen cyanide from tobacco smoke.

Although the invention has been described in considerable detail withparticular reference to certain preferred embodiments thereof,variations and modifications can be efiected within the spirit and scopeof the invention as described herein above.

We claim:

1. A rod-shaped filter element adapted for selective removal of hydrogencyanide from tobacco smoke which comprises compacted cellulose acetatefilaments enveloped in an encircling wrapper and having as a particulateadditive thereon particles selected from the group consisting ofcellulose acetate, cellulose, methyl cellulose, and starch, whichparticles are coated with a water-soluble inorganic salt selected fromthe group consisting of sodium carbonate, potassium carbonate, sodiumphosphite, and potassium phosphite.

2. The tobacco smoke filter element of claim 1 in which the coatedparticulate additive comprises 5% to of the weight of said element andthe inorganic salt comprises 2% to 10% by weight of said element.

References Cited UNITED STATES PATENTS 2,172,946 9/ 1939 Sutter 131-2653,021,242 2/ 1962 Touey 131-267 X 3,101,723 8/1963 Seligman et a1.13l-266 3,217,719 11/1965 Spears et al. 3,320,961 5 1967 Hughes et a1131-267 2,832,351 4/1958 Hale 131-10.9 2,854,473 9/1958 Spaulding et al.252446 X 2,923,378 2/1960 Braunl-ich 183114.2 3,199,946 8/1965 Fujita etal. 252-427 X 3,368,566 2/1968 Avedikian 131-10.9 X

FOREIGN PATENTS 760,772 11/ 1956 Great Britain.

ALDRICH F. MEDBERY, Primary Examiner.

D. J. DONOHUE, Assistant Examiner.

US. Cl. X.R. 131-267

